The Letter to the Ephesians is comprised of two distinct parts that can be labelled "theology" (Ephesians 1-3) and "ethics" (Ephesians 4-6). These sections are, however, difficult to reconcile with each other. The moral exhortations of the paraenesis are not directly and argumentatively derived from the theological narrative. Although Ephesians is a letter, epistolary analysis does not lead to an explanation of how the "theological" and "ethical" sections can be integrated. A rhetorical critical examination, however, provides a new angle of interpretation that shows a way through the difficulties of explaining how the two halves of the letter are related to each other. Ephesians is a document that can be designated as "sermon". As a "sermon" it is a combination of epideictic and deliberative rhetorical genres that does not address a specific issue or controversy. It speaks to a Christian audience that is not expected to make critical decisions based on argumentation within the "sermon," but rather is reminded of, impressed with, and identifies with certain theological concepts. A frame of mind is thereby developed among the audience members that makes them receptive to the moral exhortations contained in the paraenesis. An analysis of the "theological" section of Ephesians reveals that a frame of mind receptive to moral exhortation is developed through the rhetorical presentation of theological notions with which the audience would be in agreement. The "ethical" section or paraenesis is not directly founded on these theological notions, but presents its own, self contained argumentation for proper conduct to an audience that has become susceptible to such behavioral appeals. It is concluded that theology and ethics in Ephesians are related by the rhetorical use of the language of what is defined as "sermon".